I'm currently reading The Glass Castle by Jeannette Walls, which includes this passage:
Then he pointed to the top of the fire, where the snapping yellow flames dissolved into an invisible shimmery heat that made the desert beyond seem to waver, like a mirage. Dad told us that zone was known in physics as the boundary between turbulence and order. "It's a place where no rules apply, or at least they haven't figured 'em out yet," he said. "You all got a little to close to it today."
And that led me to a search for information on this zone. It seems to be a reference to the Reynolds number, which has something to do with the line between laminar and turbulent flow. And that led me to this video.